Project "Marginal gains..."
Turbo Mini Forums

Hi Robert,

Pretty much as you suggested



The main thing to do would be to connect the subframe tower bolt back to the 'A' pillar area, ideally directly to the cotton reel type thing and not just to sheet metal around that area as that adds little or no overall torsional stiffness - but some regulations don't allow you to do this.

The red and the blue tubes are typical of a roll cage added to a road car, joining the tubes at point 'C' which is sort of a halfway house as it means the std dash can remain and any door tubes are low enough to get in and out more easily but the junction is halfway down the 'A' pillar tube and not best for stiffness.

Point 'A' is more of a race car no compromise position the dotted tubes all connect where the 'A' pillar tube bends up past the screen and the tubes across the door are much less convenient for getting in and out but best for stiffness.

Another important thing is that both of the blue tubes are straight and not bent around the inner arch shape, obviously dependent on wheel widths / offsets but even in in position 'C' it is possible to put a straight tube in that just misses the tyre on full lock and full bump travel.

The yellow tube is a different matter as there is no way to put a fully straight tube in, in a ideal world I'd do a torsion test with and without this tube as I suspect it is limited in the stiffness gain versus the weight added but the Migs had it in anyway as its relatively low in the car. But again it should go directly to the cotton reel and not just in the vicinity.

The problem with doing anything like this in a road car without a cage is connecting the cotton reels back to anything that is going add any real stiffness benefit. The dash bar at point 'C' really needs to either go into the 'A' pillar part of the bodyshell and not just welded to the top skin even with a spreader plate, maybe add a couple of horizontal plates inside the 'A' pillar where the dash tube will attach just so the two are better connected.

Connecting the two cotton reels together with a straight tube across the car could help as well as the sheet metal crossmember gets pretty small in section at the centre - especially the post mk3 cars with the bigger cut out for carb clearance.

This second picture shows a similar cotton reel type arrangement in the Miglia crossmember.



The third picture isn't actually a Miglia as I couldn't find an internal photo of what I wanted to show. It however shows how a tube goes across the toeboard and the lower subframe mounting bolts are integrated into to it, not visible in this image but it also sweeps further up the toeboard and stiffens up the rack mounting area.



I think all of this is pretty common on all the Miglias now but some of these photos are nearly 10 years old.

Sorry I went on a bit :)

Cheers

Edited by Aubrey_Boy on 11th Jul, 2017.

fascinating ,thank you ,certainly helps me understand the soggy pudding feeling when cornering over 120 mph .

very hard to tell what each end is doing and is basically a bit tip toe , racing my friends caterham superlight is a bit if a humiliation lol.(unless in a straight line !!)

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Before the days of FEA it was standard practice to fix lengths of fishing line between any points you were suspicious of (just enough tension to keep them taught) and then apply a torsional load to the shell and observe which of the fishing lines went slack. That way you slowly built up a picture of what was moving relative to what.

I just bolted the subframe in using the tower bolts and attached some fishing line from the tower bolt area to the corner of the windscreen / scuttle and pulled the subframe up and the fishing line goes slack, I taped a rule to the same area and you can roughly see how much the fishing line dips.

Then I gradually built the scuttle / the corner scuttle infills, the main flat bulkhead panel etc... and you could see which bits add stiffness and those which don't - hardly scientific but you can do something similar with DTI's and a few brackets to get relative displacements.

But make sure you remove any DTI's from the bodyshell before you weld anything as I managed to fuse the internals of a DTI once even though it was nowhere near where I was welding :(

Cheers

do you think an internal tube ,running from the back of the bulkhead as near as possible to the area where the sub bolt is , running down to meet the floor a ft along the sill would help? might make it a little awkward to get in and out though.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Not completely sure I have interpreted what you said correctly... If you ignore the fact that the tube I have added looks like it is going to the dash switch panel and that it is actually pointing at the tower bolt area - is this what you meant?



So I have begun my attempt at tying the attachment of the subframe to the bodyshell a little better, at this moment in time I just intend to link back to the dash tube and also down to the tube which will attach to the top wishbone. The tube added here is 450g per side, I doubt I'll get all done with just 2kg, maybe 3kg.

I will tidy the holes in the inner arch once its all ready to weld in

I am just going to get the tubes cut to length and get them all the notched and then try and figure out how on earth I can get to weld all the way around each of the tube joints without having to cut the shell up to give access

Cheers

Edited by Aubrey_Boy on 17th Oct, 2017.

yes that was what I meant, but I was imagining it would be a much more acute angle , eg 45 degr angle vertically to the sill, so I imagined that a bit erroneously!

Edited by robert on 18th Oct, 2017.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

So because the dipstick will have to be moved as the sump will have no depth in its original position and the fact that the turbo is in such a restricted space I have decided to remake the breather so as to do away with the rubber hoses as I suspect it will get 'kin hot.

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We used a Wiggins clip to connect the two halves



Clearance to the bonnet is also improved and the water feed from the thermostat to the rad has got to get through this space as well.




It saved a bit of weight too



Cheers

Edited by Aubrey_Boy on 11th Jul, 2017.

What do you use to get those nice bends?

going back to your cage / bulkhead mods heres what mine looks like, again a ten yr old design though.

and in the last one you can see some of the horizontal bars that go from dash to bulkhead and the one that comes down the inner wing and terminates by the subframe bolt

Here for the craic..

Supercharged Arden powered

Hi Slater,

It was just a common 'pipe' bender that was used, it's only 1mm thick ally and the bends are quite gentle so it was quite straight forward.

Cheers Richspec, thanks for the Pics,

Do you have any idea of the weight of your car there doesn't seem to be too many XE conversions that I have seen weighed

Cheers

no I don't sorry, but I'd be interested to find out, I'll look into it :)

Here for the craic..

Supercharged Arden powered

Have you got a build diary on here, I know the XE has never been as popular or as common as the Honda conversions but they seem to be a dying breed even more so now, very little activity that I can see, I think there probably 3rd behind Rover K series now as well in terms of numbers.

there was one on here but mainly on 16v miniclub forum

Here for the craic..

Supercharged Arden powered

I guess compaired to the KSeries they are a heavy engine. Plus the k is plentiful and cheap at the scrapers at the mo.

As for the Honda everyone loves the vtec yo!

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I paid £10 for my 1.8 K series....

If you buy the donor car wisely it is quite easy to come out of it with a free engine and some cash on top but you do have the hassle of having to strip / break and sell the parts.

My first red top came from a £280 Calibra which gave me a base engine and money on top. It just looked like Steptoe's yard for a few weeks.

My plan originally was a G13B Suzuki but Swift Gtis are few and far between and I ended up with what is the polar opposite.

Surprised you didn't go for a Z18XE1, its what was going to go into mine after the C16XE. Red top's torque curve doesn't really work with mini's, perfect for escorts though... hence the price of the engines, blame the Gp4 guys.

Although, you'll be able to cal a full load curve on that sq6 I assume, so my previous statement is irrelevant.

Weight is just a lot lower on the small blocks. And they fit better.

I just kept going around in circles with engine choice, As I think I have mentioned before engines are really not my thing I have no allegiance either way so was happy to use whatever best suited, be it Honda, Vaux, Rover etc...

I find engine stuff massively frustrating compared to chassis stuff, just trying to find something simple like bare engine weights can result in hours of wasted time and still not have a clear answer.

I looked at the Z18XE, weight would be my only reason but like most I certainly couldn't find any data. I think all of the suitable Vaux donors are iron blocks so not sure what the weight saving would be Z18 <> C20.

I guess if I had decided on Turbo from the outset then B16/B18 was a more logical choice as far as the knowledge and parts availability goes for boosting a relatively std engine. But weight is the same if not slightly heavier than an XE from the Internet data I have found. Gearing is the worst of all the conversions though without forking out £600 for a FD.

I was pretty close to buying a VVC K series on the basis that I could weigh it / measure it up and use it in my Midget if I didn't use it in the Mini but my biggest doubt was a proper diff for an R65 or PG1. My experiences with Torsen / ATBs is not good especially as you up the torque. So I needed the failsafe option of a Salisbury plate diff and other than a company called 'Gripper' (who?) I couldn't see an option - I am talking mainly about track use, so open diff = useless and ATB not much better IME.

I think if your going to aim for 150 - 160 Hp from an NA donor then the VVC makes most sense, lightweight, can use std inlet, good FDs especially R65, cheap, fits in std length without extensive bulkhead mods, but as I say no idea what a Z18 weighs.

Cheers

Edited by Aubrey_Boy on 27th Aug, 2014.

38kg between C16XE and C20XE iirc. More if you compare them with gearboxes.

X/Z18XE1 is the same as the C16 with slightly longer stroke and a better head, cant imagine it weight any more than the C16, crank might have a longer stroke but its tidier.

Will see 200bhp from an X18 with mild cams and ITBs, had been a couple of successful turbo X18's on migweb too.

Could be good to get mark off here to weight his engine to confirm.

Hi Alex,

Thanks for the info

If your weight for the C16XE (Or rather the difference as I have my own measured accurate weight for the 20XE) is correct then the C16XE and by your inference the Z18XE are then about 97kg...

Any idea what the F13/15/17 gearboxes weigh compared to the large block boxes? I would probably have to fit a large block gearbox anyway and faff with clutch etc to adapt the two.

The Rover K series weights I have seen quoted are in the range 90 - 96 Kg, making these two Vaux engines as near as damn it the same as the K series? It doesn't seem likely the an iron block Z18 1800cc Twin cam is the same as a 1800 K series? Or maybe it is? If they were this light I would have thought it would be common knowledge, maybe it is?

I am not getting at you, so please don't think I am but this is the whole basis of my frustration with getting this kind of data.

I just Googled C16XE vs C20XE weights and some threads quote as little as 10 - 15 kg difference and some 35kg nearer to your figure but few if any quote figures they have measured themselves and what was actually included in the weight. Apologies as you may well have a known source for your weight data

Do the engine weights include...

All of the items below are from my XE and weighed

PAS pump (3kg)
Oil (4 litres = 3.5kg),
IM & TB (My ITB's are just under 4kg w/o trumpets / air filter or airbox, something like twin webers can be nearer 8 kg with linkages / airbox!)
intermediate driveshaft and inner CV (5.5kg)
exhaust manifold etc (6kg typically)
XE std Alt & Brkt (5.5kg) N.Denso are 2.5 - 3.0 kg
MAF (0.7 kg)
Coil pack (1 kg)
Pot flywheels (on later XE's are just under 10kg, early flywheels are 6kg)
Clutch / cover (5 kg)
Starter (3kg)


All of the above can give over a 40kg weight variation for the same engine depending on what is / is not included.

But you are right, if the Z18 is only 97kg (38 kg lighter than my 20XE in the same condition) and if it would happily take enough boost to deliver 250 -275 Hp I made the wrong choice (again)

Cheers

Edited by Aubrey_Boy on 27th Aug, 2014.

Think a mate has one at the moment, ill see if he can stick in on some scales later and will let you know. And sent another friend a message who might have the weight written down. It would be good to get a weight for both rather than a delta.

It's no faff to go to a small block box btw, you just wouldn't want to with your torque as you said.

Edited by alexcrosse on 27th Aug, 2014.

Sorry I meant using the Z18 with a large block Gear bag (Which would be needed if boosted) which I think just means getting a clutch / cover to suit the output spline / shaft.

Would be interesting to get the Z18 weight in a known condition, I always take a photo as it's the best way of remembering what was still on the engine as I always forget something which was or wasn't still on it.

I couldn't possibly ask MarkGTT to weigh his as it would mean taking it out of the car and I don't want scratching that paintwork on my concscience :)

Cheers

Yeah don't really fancy taking it back out of the car! I have a few other blocks in the shed - one being a C16XE, If I can get something suitable to weigh it with I will let you know.

Cheers Mark

I can probably get hold of some proper corner weight scales for a few days when the race season is over in a month or so

So between the shear panel, subframe, downpipe, intermediate shaft and RH inner CV we have to squeeze something in that resembles a sump.

This is where it is so far



I've calculated the volume and basically have tried to grab whatever area possible, once it's welded up I will double check the volume and try and figure out where to put the drain plug and dipstick access.

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The main area as far as depth goes is to the rear which I think is preferable

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The area which extends rearwards is limited in height by the RH inner CV and the intermediate shaft.

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Once I am happy that the volume and other stuff is OK we will look at dividing / baffling it, then hopefully on to the inlet manifold.

Cheers

Edited by Aubrey_Boy on 11th Jul, 2017.